The present invention relates to a continuous cigarette rod manufacturing machine.
Known cigarette manufacturing machines of the aforementioned type feature a substantially vertical duct supplied at the bottom with a continuous flow of tobacco particles, and closed off at the top by the bottom branch of a suction conveyor on which a layer of tobacco is formed. The said layer of tobacco is then transferred by the said conveyor into a position outside the said vertical duct and over a horizontal surface or bed for forming the said continuous cigarette rod.
In the said latter position, the layer of tobacco is fed on to a strip of cigarette paper travelling along the said forming bed, via the interposition of the top branch of a belt in the form of a loop and made of textile material permeable by air.
The paper strip is wound off a reel and, prior to utilization, is first fed through a number of operating units, which may include, for example, a splicing device, one or more printing devices, and various control devices. Guiding of the paper strip and textile belt on the forming bed is performed by a single pulley.
As the paper strip travels along the said forming bed, the textile belt causes it to fold gradually crosswise, so as to form a continuous tobacco-filled cylinder commonly known as a continuous cigarette rod, which is subsequently cut into single cigarettes.
The poor efficiency of machines of the aforementioned type is due to the work involved in threading the paper strip along a route which, as already seen, is both long and complicated.
This is done manually by the operator at the start of each shift, or whenever the paper strip tears, and is even more complicated in the case of dual-rod machines, i.e. for simultaneously producing two continuous cigarette rods. U.S. Pat. No. 4,336,813 filed by the present Applicant, G. D. S.p.A., proposes a solution to the problem by partly automating threading of the paper strip along the said route.
According to the said patent, the cylindrical surface of the guide pulley at the input to the rod forming bed is connected to a suction source. Consequently, all the operator has to do is place the end of the paper strip, or strips, in the case of a dual-rod machine, next to the guide pulley, which sucks the strip on to its outer surface and, as it turns, feeds it on to the rod forming bed. Once the machine has been started up, the guide pulley is disconnected from the suction source, and the paper strip is fed along the forming bed by the combined action of the textile belt and the tobacco layer alone.
In the light of U.S. Pat. No. 4,336,813, the operator is still required, in the event of the paper strip tearing, to thread it through the various operating units already mentioned. As, during normal operation of the machine, the paper strip is fed forward by the combined action of the textile belt on its underside and the tobacco layer on its top side, any shortage or substantial variation in the flow of tobacco on the strip results, firstly, in swerving and, eventually, in tearing of the paper strip.
This is tantamount to saying that a shortage in tobacco supply and, particularly, clogging inside the suction duct or elsewhere on the machine, are indirectly responsible for tearing of the paper strip.
In the event of this happening, in addition to clearing the clogged section, the operator is also called upon to perform the painstaking job of threading the paper strip through the operating units already mentioned, so as to bring the end of the strip into contact with the guide pulley at the input of the rod forming bed.